[An update has been posted below, with Microsoft saying the Windows RT 8.1 update problems is affecting a small percentage of Surface RT users. It did not say when the update will be available again in the Windows Store.]

Only a day after announcing that the Windows 8.1 update was available for download, Microsoft on Friday pulled the Windows RT 8.1 update from the Windows Store.

(Windows RT is a variant of Windows, a sort of “Windows lite” designed to run on devices, such as tablets, using power-sipping ARM processors.)

On Friday, a company representative had said in a Microsoft community support forum that: “Windows RT 8.1. Microsoft is investigating a situation affecting a limited number of users updating their Windows RT devices to Windows RT 8.1. As a result, we have temporarily removed the Windows RT 8.1 update from the Windows Store. We are working to resolve the situation as quickly as possible and apologize for any inconvenience. We will provide updates as they become available.”

Microsoft has not said when the update will be available again in the Windows Store.

It appears that in addition to whatever is ailing the Windows RT 8.1 update, that quite a few people are having problems with the Windows 8.1 update as well. In replying to an official Microsoft blog post announcing the update, some commenters said they were having trouble installing the update; or that after they updated to Windows 8.1, Office was deactivated on their machines or that the colors on certain games and apps appeared strange.

[Update 11 a.m.: Microsoft says the Windows RT 8.1 update problem is limited to a small percentage of Surface RT users. It’s providing recovery media for those users who’ve already been affected. But the company hasn’t yet said when the update will be available again in the Windows Store. Here’s the statement from Microsoft:

Based on our investigations of a situation customers have encountered updating to Windows RT 8.1, we can confirm that as of now this is a Windows update issue only affecting Surface RT customers.

While only less than 1 out of every 1,000 ( or less than 0.1%) Surface RT customers who have installed Windows RT 8.1 have been impacted, improving their experience and ensuring their systems are fully operable as quickly as possible is our number one priority.

Those who can’t find the update should go here. And he is referring those with general questions about the update to this FAQ.

Several commenters have asked for the ISO images for the update, rather than having to update through the Windows Store. LeBlanc says Microsoft is not releasing the ISO image except to people who have MSDN and TechNet subscriptions.]

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Welcome to Microsoft Pri0: That's Microspeak for top priority, and that's the news and observations you'll find here from Seattle Times technology reporter Matt Day. Send tips or comments to mday@seattletimes.com.